It’s only been a few days since SpaceX boss Elon Musk fired off a tweet reminding everyone that he wants to “nuke Mars,” but he’s already offered a possible alternative to that wild proposal. In a tweet on Tuesday, Musk proposed launching thousands of solar reflectors to the Red Planet in order to heat up the planet’s surface, melt its reserves of ice, and release CO2 that could help form a more robust Martian atmosphere.

Humans are headed to Mars sooner rather than later, but what we’re going to do once we get there remains to be seen. Dreams of establishing a colony on Mars may depend on our ability to make Mars a bit more like Earth, and that would mean beefing up the atmosphere.

Scientists believe there’s a wealth of CO2 trapped in the ice Mars still has around its poles, but whether there’s enough CO2 to make a serious difference for the planet’s atmosphere is a topic of debate. Musk insists there is, and his idea to “nuke Mars” would mean initiating nuclear explosions above the planet to serve as an “artificial sun” and heat the planet, melting the ice.

It’s a wild idea, but Musk’s second proposal seems a bit more within the realm of possibility.

Instead of creating tiny fake stars using nuclear weapons, Musk suggests that satellites could reflect sunlight onto Mars and heat it up that way, but doing so would require thousands of such satellites. The benefit of this approach would be that it could be done gradually and that adjustments could be made along the way.

Still, without knowing for sure if melting the polar ice on Mars will have a serious impact on its habitability, such a mission remains purely hypothetical.